Conventionally, a so-called laminated evaporator has been widely employed as an evaporator for use in a car air conditioner. In the laminated evaporator, a plurality of flat, hollow members, each of which includes a pair of depressed plates facing each other and brazed to each other at their peripheral edge portions, are arranged in parallel, and corrugate fins are each disposed between and brazed to the adjacent flat, hollow members.
In recent years, evaporators have been required to be further reduced in size and weight and to exhibit higher performance. A known evaporator which fulfills these requirements includes a heat exchange core section configured such that heat exchange tube groups are arranged in two rows in the front-rear direction, each heat exchange tube group consisting of a plurality of heat exchange tubes arranged at predetermined intervals; a refrigerant inlet header section which are disposed on the upper-end side of the heat exchange tubes and to which the left half of the heat exchange tubes of the front heat exchange tube group are connected; a refrigerant outlet header section which is disposed on the upper-end side of the heat exchange tubes to be located on the rear side of the refrigerant inlet header section and to which the left half of the heat exchange tubes of the rear heat exchange tube group are connected; a first intermediate header section which is disposed on the lower-end side of the heat exchange tubes and to which the heat exchange tubes of the heat exchange tube group connected to the refrigerant inlet header section are connected; a second intermediate header section which is disposed on the right side of the first intermediate header section and to which the remaining heat exchange tubes of the front heat exchange tube group are connected; a third intermediate header section which is disposed on the upper-end side of the heat exchange tubes to be located on the right side of the refrigerant inlet header section and to which the heat exchange tubes connected to the second intermediate header section are connected; a fourth intermediate header section which is disposed on the upper-end side of the heat exchange tubes to be located on the rear side of the third intermediate header section and to which the remaining heat exchange tubes of the rear heat exchange tube group are connected; a fifth intermediate header section which is disposed on the lower-end side of the heat exchange tubes to be located on the rear side of the second intermediate header section and to which the heat exchange tubes connected to the fourth intermediate header section are connected; and a sixth fifth intermediate header section which is disposed on the lower-end side of the heat exchange tubes to be located on the left side of the fifth intermediate header section and to which the heat exchange tubes connected to the refrigerant outlet header section are connected. Refrigerant which flows into the refrigerant inlet header section passes through the heat exchange tubes and the first through sixth header sections, flows into the refrigerant outlet header section, and then flows out of the refrigerant outlet header section (refer to Japanese Patent Application Laid-Open (kokai) No. 2003-214794).
In the evaporator disclosed in the publication, the first intermediate header section and the second intermediate header section are integrally provided in a single header section, the fifth intermediate header section and the sixth intermediate header section are integrally provided in a single header section, and refrigerant flows into the second intermediate header section and the sixth intermediate header section from their longitudinal end portions.
However, in the evaporator disclosed in the publication, refrigerant having flown into the second intermediate header section or the sixth intermediate header section tends to flow toward the deeper side within the intermediate header section, and becomes less likely to flow into heat exchange tubes connected to the refrigerant inflow side of the intermediate header section. As a result, refrigerant becomes less likely to uniformly flow into all the heat exchange tubes connected to both the intermediate header sections. Therefore, the distribution of refrigerant within the heat exchange core section becomes non-uniform, and the temperature of air having passed through the heat exchange core section becomes non-uniform in some locations, so that the heat exchange performance is not improved sufficiently.
An object of the present invention is to overcome the above problem and to provide a heat exchanger which exhibits excellent heat exchange performance.